Nonlinear electromagnetic and gravitational actions of neutron star fields on electromagnetic wave propagation

The nonlinear electrodynamic and gravitational actions on the weak electromagnetic wave propagation in the strong dipole magnetic and gravitational fields of a neutron star are discussed. The eikonal equations for an electromagnetic wave propagating in the external field as well as the motion equations of photons in the dipole magnetic and gravitational fields of a neutron star are obtained from the parametrized post-Maxwellian electrodynamics of the vacuum, which is analogous to the parametrized post-Newtonian theory of gravitation. The solution of these equations indicates that electromagnetic signals, carried by normal waves with mutually orthogonal polarization, travel along different rays and take different time to reach the detector from the same source. It is also shown that in appropriate conditions the value of this nonlinear-electrodynamic lag can be about a tenth part of a microsecond. A detailed analysis of the possibilities of observing this effect by the detection of X-rays and gamma rays from pulsars and magnetars was made